Electron discharge device



Nov. 1, 1932. L. BEGIN ELECTRON DISCHARGE DEVICE a-vwem toz LUCIEN BEGIN 35 his/ flbtomu v a E g/v l 3. MM

Filed March 2, 1926 Patented Nov. 1 1932 UNITED TAT LucIEiv'BEGIN, or PARIS, FRANCE, .AssIGNoRor oNE-rrALF re W L IAM 3. WEAVER,

or BIRMINGHAM, ALABAMA, iAN D HAROLD r. WILHELM, OF'NEW YORK Emerson DISCHARGE Dawes f A pnet on filed Mam, 1926, Ser ia1. No 91,670, and in I ir ance March 14, 925.

"The present invention relates to a new method of supplying current to the electrodes of'hermetic tubes and'more particularly to the cathodes of high-power thermionic tubes.

' It isknownthat the construction of-high power tubes of the order of 50 kilowattsor more involves, in addition to the use of special coating of'the cathodes with a view of increasing their electron emitting power, the

do use of cathodes of large area and operating at high temperature whichfimplies an ap-' preciable power eXpenditureior the heating of said cathodes, As a general rule, the heating is eflected electrically and',"mainly'for constructional reasons, at relatively low j voltages. Now, whenever it is desired to lead in large currents through thewalls ofa vacuum tube, it is necessary to'use lead-in conductors of such dimensions that the'seal- 7 ing of same through the tube walls offers great'difiiculties in maintaining the tube in a hermetic condition owing to the, uneven expansion of'the le'adin'conductors andof the insulating material of the tube envelope.

In accordance with the invention, the seals heretofore used may be partly or entirely suppressed and the insulating walls of'the tube envelope used as-the dielectric of two condensers hooked upin' series internally 7 so through the cathode oryother'body which it is desired to bring to incandescence.

-Iirthedrawing; V Fig. 1 represents a three-element electron .1 discharge device according tothe invention whose cathode heating current is supplied thru condensers which utilize the envelope astheir dielectric,"the devicehaving cooling means for controlling the operating tempera ture. j 1 40 Fig. '2 illustrates a hook-up which may be used with an electron discharge device of the type shown in Fig. 1 according to the invention.

Fig. 3 illustrates another manner in which an electron discharge device may be con,- structed. according to the invention, and 1 Fig. & illustrates an electron discharge device having a hook-up for supplying the cathode with both alternating and direct heating current.

" Referring nowito Figure 1,--V, designates the envelope having a middle branch andftwo .suitable voltage and frequencyas well as for the; proper dissipation of the power expended through joulean effect and dielectric hysteresis." The inside walls of the side branches are coated'withconductive coatings Az', A11, and the outside surfaces thereof are also covered by similar coatings Ae, Ae having'connections at Fa, F a; The inside coatings. Ac, 7 A'c', areconnected togetherthrough the cath- .5

ode intended tov absorb the power. transmitted through the tube" dielectric. 'Theanode and, c

grid are respectively connected to terminals P, G, and a suitablepoin-t.of thecathode, in -V tended to complete thepath ofthe direct ourrent resulting rom the'transfer" of, negative charges from cathode to anode, is connected; to a'third terminalFc. v The power. expended within the tube may be dissipated by causing the three branches of the tube to be immersed inrefrigerating tanksH, H, H, in accordance with a known process.

The dynamic I I coatings Az',- Ae,;tlirough electrostatic attracstresses exerted between the tion, will be far less than those which occur in known electromagnetic inductive heating methods comprising inside and outside coils, and it will only'be necessary that thecoatings be uniformlya'dherent to the walls of'the vessel. The form shown in Figure 1 is quite schematic and it will be possible to adopt any other shape whatever susceptible of fulfilling the conditionsabove described, exercising due care, however, to; avoid shaping the vessel to make use of a substance which, whilst possessing a high specific inductive power, will. be as little conductive as possible and capable such as it would become fragile and difficult of. withstanding igh emperatures, such as;

quartz, pyrexglass or mere silica containing a slight proportion of uranium. For that matter, it is not necessary to carry out the whole structure with one and the same substance, it being possible to construct each of the various parts with that substance which most suits its particular needs.

In order to avoid electrical concentration in the dielectric region comprised between the inside and outside coatings, Az', A0, it will be possible to distribute the potential gradient within the dielectric by means of conducting surfaces inserted at suitable intervals in the dielectric and in planeparallel to that of the coatings in a manner similar to a known process.

Referring now to Fig. 2, the outside coating terminals Fa, Fa, are connected to a highfrequency source HF (eventually an ordinary damped wave generator) through a tuning inductanceLf, an ammeter A and a transformer Tf. The anode P is connected to the terminal F'c of the cathode through the anode potential source E79 and a portion of the auto-transformer Lp. The other extremity of Lp is-connected to the grid G and the total winding is branched across a condenser Instead of leading in the total cathode heating current through the dielectric, it will be possible to introducepart of it conductively by means of wires sealed through the walls of the vessel and connected, on one hand to the cathode terminals and, on the other hand to either the same source HF or to an independent direct current source. In the latter case, however, care will have to be exercised in order to avoid that the high-frequency currents may not surge back into the direct current source.

In Figure 4 there is illustrated a method of supplying the cathode by the simultaneous use of a direct and of high-frequency current sources. In this figure, the high-frequency alternating current source I-IF is branched between the middle-point of the cathode through transformer Tf, tuning 'inductance Lf and an input condenser utilizing the wall of the tube as dielectric and to the two extremities of the cathode through transformer Tf, ammeter A and the input condenser in series with each cathode extremity and also utilizing the wall of the tube as dielectric.

The direct current source E7 is connected to the extremities of the cathode through an adjusting rheostat Rf and an ammeter A, the gridcathode-anode connections being effected in a manner similar to that of Figure 2 or in accordance with any known diagram. The condenser in series with the middle point of the cathode and the inductance Lf will preferably be provided with a capacity equal to the sum of those of the condensers in series with the cathode extremities. If the latter are equal to each other,

it will be seen that the two extremities of the cathode will be equipotential from the point of view of the alternating E. M. F. applied thereto and the direct current source Ef may be connected directly in shunt thereto.

Instead of being carried out with a single tube comprising three input condensers, the diagram of Figure 4- may be realized by means of two tubes of the type described in Figure 3 and each comprising but two-input condensers. It will only be necessary to connect the tubes in series as regards the input condensers and to connect the high-frequency source between the tie, linking the two tubes in series and the two extremities connected together. The direct current source should then be connected across the extremities of the two cathodes afterthe latter have also been conductively connected in series. It will be seen that this amounts 'to decomposing thesingle cathode of Figure 4- into two distinct cathodes having a common leadin connection corresponding to the 'middle supply connection and input condenser. In

the case where it would be desirable to con- 1 trol the electron flow by means of the variable magnetic property of the cathode itself, the latter may be made rectilinear; in other cases, it should preferably be wound in zigzag so as to make it non-inductive.

While the invention has been described but in its application to the supply of current to the cathode of a thermionic tube, it must be understood that it may also be applied to any case in which it is desired to introduce large currents within hermetic insulating vessels. It may be used particularly for introducing the large heating currents used for purging the electrodes during the process of evacuation. 7

Having described my invention, I claim:

1. In combination, an envelope" ofv dielectric material-having an electric device therein, means for leading alternating current en ergy to said device including a'condenser whereby said dielectric material is used as the dielectric of said condenser, and means for leading direct current energy to said device.

2'. An electron discharge device comprising an envelope having a tubular body, a middle tubular branch and parallel end tubular branches, the free ends of said end branches being rounded, tubular condenser plates on the inside and outside of said end branches, said plates being rounded to fit said free ends, a filamentary cathode, an anode and control electrode in said middle branch, said filamentary cathode being connected to said inside plates, said body having I cooling fluid in which mersed.

8. An electron discharge device comprising an envelope ofdielectric material, a cathode therein, means'for leading energyto said cathode including a condenser Whose dielectric forms part of said envelope ananode, between which and saidfca'thode space current is adapted to flow, and conducting means extending to said cathode for leading the space current away from said. cathode to a point external to said device.

LUCIEN BEGIN.

said branches are im- 

